Good day, guys. I’m sitting analyzing the architecture of VIP. I can’t figure out how to pass data back from the second view controller?

My example file GitHup

import UIKit

protocol IFirstRouter {
    func nextView(dataTransfer: TranswerAnimalModel)
    func errorView(errorText: String)
}

final class FirstRouter {
    weak var viewController: UIViewController?

    internal init(viewController: UIViewController?) {
        self.viewController = viewController
    }
}

extension FirstRouter: IFirstRouter {
    func nextView(dataTransfer: TranswerAnimalModel) {
        let secondVC = assemblySecondView()

        secondVC.dataTranswer(dataTranswer: dataTransfer)
        viewController?.navigationController?.pushViewController(secondVC, animated: true)
    }

    func errorView(errorText: String) {
        let alertView = createAlert(error: errorText)
        viewController?.present(alertView, animated: true, completion: nil)
    }
}

extension FirstRouter {
    func createAlert(error: String) -> UIAlertController {
        let alert = UIAlertController(
            title: "Alert",
            message: error,
            preferredStyle: .alert
        )
        alert.addAction(UIAlertAction(
            title: "OK",
            style: .default,
            handler: nil
        ))
        return alert
    }
}

import UIKit

protocol ISecondViewDisplay: AnyObject {
    func render()
}

protocol ITranswerView {
    func dataTranswer(dataTranswer: TranswerAnimalModel)
}

final class SecondViewController: UIViewController {

    // Подключаем SecondIteratorProtocol протокол
    // MARK: - External vars
    var router: ISecondRouterLogic?

    // MARK: - Internal vars
    var iteractor: ISecondIterator?

    private lazy var buttonFirstName: UIButton = createButton("DOG")
    private lazy var buttonSecondName: UIButton = createButton("BEAR")

    private lazy var labelTitle: UILabel = createLabel()
    private lazy var labelIcon: UILabel = createImageLabel()

    private lazy var navigationBar = UINavigationBar()
    private lazy var backButton: UIBarButtonItem = createButtonNav("Back")

    private lazy var hStack: UIStackView = createHStack()

    private var dataDisplay = TranswerAnimalModel(titleAnimal: "", iconAnimal: "")

    init() {
        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        setupConficuration()
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        setupLayout()
    }
}

extension SecondViewController: ITranswerView {
    func dataTranswer(dataTranswer: TranswerAnimalModel) {
        dataDisplay.titleAnimal = dataTranswer.titleAnimal
        dataDisplay.iconAnimal = dataTranswer.iconAnimal
        reloadDisplay()
    }
}

// Инициализация View
private extension SecondViewController {
    func setupConficuration() {
        view.backgroundColor = .white
        title = "Second screen"

        self.navigationItem.leftBarButtonItem = backButton

        backButton.action = #selector(didTapButtobBack)
        buttonFirstName.addTarget(
            self,
            action: #selector(answerDog),
            for: .touchUpInside)

        buttonSecondName.addTarget(
            self,
            action: #selector(answerBear),
            for: .touchUpInside
        )

        view.addSubview(labelTitle)
        view.addSubview(labelIcon)

        hStack.addArrangedSubview(buttonFirstName)
        hStack.addArrangedSubview(buttonSecondName)
        view.addSubview(hStack)
    }
}

// Подключение протокола SecondViewDisplayLogicProtocol
extension SecondViewController: ISecondViewDisplay {
    func render() { }
}

// Инициализация VIP
extension SecondViewController {
    private func setup() {

    }
}

// Создание UI элементов
private extension SecondViewController {
    private func createButton(_ text: String) -> UIButton {
        let button = UIButton()
        button.configuration = .filled()
        button.configuration?.cornerStyle = .medium
        button.configuration?.baseBackgroundColor = .gray
        button.configuration?.title = text
        button.translatesAutoresizingMaskIntoConstraints = false

        return button
    }

    private func createButtonNav(_ text: String) -> UIBarButtonItem {
        let button = UIBarButtonItem()
        button.image = UIImage(systemName: "arrowshape.backward.fill")
        button.title = text
        button.style = .plain
        button.target = self
        button.tintColor = UIColor.black

        return button
    }

    private func createImageLabel() -> UILabel {
        let label = UILabel()
        label.text = ""
        label.font =  UIFont.systemFont(ofSize: 120)
        label.textAlignment = .center
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }

    private func createLabel() -> UILabel {
        let label = UILabel()
        label.textAlignment = .center
        label.textColor = UIColor.black
        label.translatesAutoresizingMaskIntoConstraints = false

        return label
    }

    private func createHStack() -> UIStackView {
        let hStach = UIStackView()
        hStach.distribution = .fillEqually
        hStach.axis = .horizontal
        hStach.spacing = 20
        hStach.translatesAutoresizingMaskIntoConstraints = false

        return hStach
    }
}

// Инициализация UI элементов
private extension SecondViewController {
    func setupLayout() {
        NSLayoutConstraint.activate([
            labelTitle.heightAnchor.constraint(equalToConstant: 20),
            labelTitle.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            labelTitle.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            labelTitle.leadingAnchor.constraint(
                equalTo: view.leadingAnchor,
                constant: 10
            ),
            labelTitle.trailingAnchor.constraint(
                equalTo: view.trailingAnchor,
                constant: -10
            ),

            labelIcon.heightAnchor.constraint(equalToConstant: 100),
            labelIcon.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            labelIcon.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 10),
            labelIcon.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -10),
            labelIcon.bottomAnchor.constraint(
                equalTo: labelTitle.topAnchor,
                constant: -20
            ),

            hStack.heightAnchor.constraint(equalToConstant: 40),
            hStack.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            hStack.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 60),
            hStack.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -60),
            hStack.topAnchor.constraint(
                equalTo: labelTitle.bottomAnchor,
                constant: 20
            )
        ])
    }
}

// Action UI элементов
extension SecondViewController {
    @objc private func answerDog() {
        dataDisplay.titleAnimal = "DOG"
        dataDisplay.iconAnimal = "🐶"
        reloadDisplay()
    }

    @objc private func answerBear() {
        dataDisplay.titleAnimal = "BEAR"
        dataDisplay.iconAnimal = "🐻"
        reloadDisplay()
    }

    @objc private func didTapButtobBack() {
        router?.returnFirstView(dataTranswer: dataDisplay)
    }

    private func reloadDisplay() {
        labelTitle.text = dataDisplay.titleAnimal
        labelIcon.text = dataDisplay.iconAnimal
    }
}

import UIKit

protocol ISecondRouterLogic {
    func returnFirstView(dataTranswer: TranswerAnimalModel)
}

final class SecondRouter {

    weak var viewController: UIViewController?

    internal init(viewController: UIViewController?) {
        self.viewController = viewController
    }
}

extension SecondRouter: ISecondRouterLogic {
    func returnFirstView(dataTranswer: TranswerAnimalModel) {
        print("dataTranswer \(dataTranswer)")
        viewController?.navigationController?.popViewController(animated: true)
    }
}